Hibernate使用EHCache二级缓存 .

数据库结构：



create table teamEH (id varchar(32),teamname varchar(32));
create table studentEH (id varchar(32),name varchar(32),team_id varchar(32));POJO：



package EHCache;

public class Student ...{
    private String id; //标识id
    private String name; //学生姓名
    private Team team;//班级




    public String getName() ...{
        return name;
    }

  

    public void setId(String id) ...{
        this.id = id;
    }

  

    public void setName(String stuName) ...{
        this.name = stuName;
    }

 

    public String getId() ...{
        return id;
    }

    public Student() ...{ //无参的构造函数
    }

  

    public Team getTeam() ...{
        return team;
    }

    public void setTeam(Team team) ...{
        this.team = team;
    }
}




package EHCache;

import java.util.HashSet;
import java.util.Set;


public class Team ...{
    private String id;
    private Set students;
    private String teamName;
    public String getId() ...{
        return id;
    }

    public void setId(String id) ...{
        this.id = id;
    }

    public String getTeamName() ...{
        return teamName;
    }

    public void setTeamName(String name) ...{
        this.teamName = name;
    }

    public Set getStudents() ...{
        return students;
    }

    public void setStudents(Set students) ...{
        this.students = students;
    }
}
Team.hbm.xml

其中<cache>标签表示对student集合缓存，但只缓存id,如果需要缓存student实例，则需要在student.hbm.xml中的
class标签中配置<cache>



<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!--
    Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
<hibernate-mapping package="EHCache" >
    <class name="EHCache.Team" table="teamEH" lazy="false">
       <id name="id" column="id">
         <generator class="uuid.hex"></generator>
       </id>
       <property name="teamName" column="teamName"></property>
      
       <set name="students"
            lazy="true"
            inverse="true"
            outer-join="false"
            batch-size="2"
            cascade="save-update"
           >
           <!-- 对students集合缓存，但只是缓存student-id如果要对整个对象缓存，
                还需要在Student.hbm.xml的class标签中加入<cache>标签 -->
         <cache usage="read-write"/>
         <key column="team_id"></key>
         <one-to-many class="EHCache.Student"/>
       </set>
      </class>
</hibernate-mapping>


Student.hbm.xml



<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!--
    Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
<hibernate-mapping package="EHCache" >
  
    <class name="EHCache.Student" table="studentEH" lazy="false">
       <cache usage="read-write"/>
       <id name="id" column="id" unsaved-value="null">
         <generator class="uuid.hex"></generator>
       </id>

       <property name="name" column="name"></property>
   
       <many-to-one name="team"
                    column="team_id"
                    outer-join="true"
                    cascade="save-update"
                    class="EHCache.Team"></many-to-one>
      </class>
</hibernate-mapping>


Hibernate.cfg.xml

配置hibernate.cache.provider_class以启用EHCache

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
          "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<!-- Generated by MyEclipse Hibernate Tools.                   -->
<hibernate-configuration>

<session-factory>
    <property name="connection.username">root</property>
    <property name="connection.url">
        jdbc:mysql://localhost:3306/schoolproject?characterEncoding=gb2312&amp;useUnicode=true
    </property>
    <property name="dialect">
        org.hibernate.dialect.MySQLDialect
    </property>
    <property name="myeclipse.connection.profile">mysql</property>
    <property name="connection.password">1234</property>
    <property name="connection.driver_class">
        com.mysql.jdbc.Driver
    </property>
    <property name="hibernate.dialect">
        org.hibernate.dialect.MySQLDialect
    </property>
    <property name="hibernate.show_sql">true</property>
    <property name="current_session_context_class">thread</property>

    <property name="hibernate.cache.provider_class">
            org.hibernate.cache.EhCacheProvider
        </property>
    <mapping resource="EHCache/Student.hbm.xml" />
    <mapping resource="EHCache/Team.hbm.xml" />

</session-factory>

</hibernate-configuration>EHCache.xml(放在classpath下)



<ehcache>


    <diskStore path="c:/cache"/>  <!--缓存文件存放位置-->

    <defaultCache
        maxElementsInMemory="10000"
        eternal="false"
        timeToIdleSeconds="120"
        timeToLiveSeconds="120"
        overflowToDisk="true"
        />

    <cache name="EHCache.Student"
        maxElementsInMemory="500"    <!---超过500实例，就将多出的部分放置缓存文件中->
        eternal="false"
        timeToIdleSeconds="120"
        timeToLiveSeconds="120"
        overflowToDisk="true"
        /> -->

    <!-- Place configuration for your caches following -->

</ehcache>


测试代码（插入准备数据部分）



package EHCache;

import java.io.File;
import java.util.List;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

public class Test ...{


    public static void main(String[] args) ...{
        String filePath=System.getProperty("user.dir")+File.separator+"src/EHCache"+File.separator+"hibernate.cfg.xml";
        File file=new File(filePath);
        SessionFactory sessionFactory=new Configuration().configure(file).buildSessionFactory();
        Session session=sessionFactory.openSession();
        Transaction tx=session.beginTransaction();
       
//        Team team=new Team();
//        team.setTeamName("team1");
//       
//       
//        for(int i=0;i<1000;i++){
//            Student stu=new Student();
//            stu.setName("tom"+i);
//            stu.setTeam(team);
//            session.save(stu);
//        }
//        tx.commit();
//       

    }

}


测试成功后，运行以下代码



package EHCache;

import java.io.File;
import java.util.List;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

public class Test ...{


    public static void main(String[] args) ...{
        String filePath=System.getProperty("user.dir")+File.separator+"src/EHCache"+File.separator+"hibernate.cfg.xml";
        File file=new File(filePath);
        SessionFactory sessionFactory=new Configuration().configure(file).buildSessionFactory();
        Session session=sessionFactory.openSession();
        Transaction tx=session.beginTransaction();
       
   
        //模拟多用户访问数据
        Session session1=sessionFactory.openSession();
        Transaction tx1=session1.beginTransaction();
        List list=session1.createQuery("from Student").list();
        for(int i=0;i<list.size();i++)...{
            Student stu=(Student)list.get(i);
            System.out.println(stu.getName());
        }
        tx1.commit();
        session1.close();   
   
        Session session2=sessionFactory.openSession();
        Transaction tx2=session2.beginTransaction();
            //这个uuid从刚才插入的数据中复制一个student的id
        Student stu=(Student)session2.get(Student.class, "4028818316d184820116d184900e0001");
        System.out.println(stu.getName());
        tx2.commit();
        session2.close();
    }

}


结果如下：

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Hibernate: select student0_.id as id0_, student0_.name as name0_, student0_.team_id as team3_0_ from studentEH student0_
Hibernate: select team0_.id as id1_0_, team0_.teamName as teamName1_0_ from teamEH team0_ where team0_.id=?
tom0
tom1
tom2
tom3
tom4
tom5
tom6
tom7
tom8
tom9
tom10
........................................

tom974
tom975
tom976
tom977
tom978
tom998
tom999
Hibernate: select team0_.id as id1_0_, team0_.teamName as teamName1_0_ from teamEH team0_ where team0_.id=?
tom0



可以看到，第二次查询，已经不再访问数据库了，而且，查看c:/cache文件夹，也可以看到，数据已经缓存成功了